Various overland vehicles or implements that are configured for harvesting a grain crop, for example (such as combines, farming equipment, and the like) can also be configured for negotiating sloped terrain. The vehicle may include cleaning or separation components to perform the desired harvesting functions. Sometimes, the vehicle may make harvesting passes along a slope that runs uphill when traversing uneven terrain. In those cases, travelling uphill can cause a significant amount of the harvested crop to fall off the back of the vehicle's cleaning components where it may be combined with tailings, and reprocessed by the cleaning components. This can be a source of reduced material flow through the vehicle.
Harvested grain that is returned as tailings during a harvesting pass (and reprocessed by the cleaning process) can also tend to overload the cleaning components, often jamming the components. This can be a particular problem when the vehicle transitions from an uphill climb to the crest of a hill, and begins its descent. The additional grain combined with the tailings is then processed along with grain being harvested. Thus, making harvesting passes while traversing hilly or sloped terrain can cause inconsistent material flow through the cleaning components of the vehicle, and create problems such as jams.
Sometimes, an operator may attempt to modulate the speed of the vehicle during harvesting passes, based on whether the vehicle is ascending or descending a hill, or making a transition in the terrain. However, this can be very difficult to do, as well as being a fairly inefficient way to harvest a field. It can be difficult to accurately time speed increases and speed decreases with the changing terrain, and can be a burden on the operator over time. Further, attempts to regulate the speed of the vehicle may not be successful in preventing harvested grain from falling off the back of the cleaning components while the vehicle is ascending a steep incline.